Natural resources such as water, for which the availability to users is random, are often shared according to predefined rules. What determines users' choice of a sharing rule? To answer this question, we designed an experiment in which subjects: (1) vote on sharing rules; (2) choose the technology that transforms the resource into payoffs; and (3) respond to a survey on their adhesion to principles of fairness. We find that although subjects tend to vote for the sharing rule that is aligned with their self-interest, they become more egalitarian if they report their views on the fairness principles before voting. Furthermore, the adhesion to fairness principles affects the subjects' votes not directly but rather indirectly through the choice of technology.